Redox‐Pathway Reconstruction in Carbonate Electrolyte to Achieve Durable Na─S Battery

ABSTRACT

The practical performance of room‐temperature sodium–sulfur (RT Na─S) batteries in low‐solubility carbonate electrolytes is fundamentally constrained by slow “solid‐solid” sulfur conversion, causing incomplete redox reactions and rapid capacity fading. Herein, we propose a catalytic strategy via “confinement‐pyrolysis” that restructures this static reaction into a dynamic “solid‐liquid‐solid” pathway. By employing a hierarchical porous framework with atomically dispersed metal sites, the conversion kinetics of sodium polysulfides (NaPSs) are dramatically accelerated. This reconstruction enables continuous liquid‐phase intermediates and circumvents the high diffusion barriers of solid‐state reactions, as confirmed by density functional theory (DFT) calculations. By simulating long‐term cycling through controlled Na ₂ S deposition, we employed local dipole moment change ( Δμ ) tracking to reveal the exceptional electronic structure stability and effective lowering of key energy barriers during long‐term cycling. As a result, the Fe‐N‐C/S cathode exhibits outstanding electrochemical performance, delivering a reversible capacity of 799 mAh g ⁻¹ at 1 Ag ⁻¹ with a capacity decay rate of 0.075% per cycle, and exhibiting an ultralow capacity decay rate of 0.024% per cycle over 2000 cycles at 2 Ag ⁻¹ . This work elucidates that redox‐pathway reconstruction is a pivotal strategy to overcome the inherent kinetic limitations of the conventional mode in carbonate‐based Na─S batteries.